Looking at the details of any item (by double clicking on it from the stock control main page) you will see that you can specify up to 6 different prices for a single item:

Note that WholeSaler Price works just like price level 6. By default, normal price is used everywhere, however it is also possible to apply any of the other prices for the item.

By Customer Account
Going into the customer account screen, you can specify which price level items will be sold for whenever the transaction is put through under the customer account. Once you specify a price level here, every item will use that price instead of normal price.

By Staff Account
If you specify a price level for a staff account, then every item that is sold while that particular staff is logged on will be applied with the price level you specified. To access this setting, from the setup page go into software setup, and then click the staff setup tab.